Detection of Significant Variation in Acoustic Output of an Electromagnetic Lithotriptor

Pishchalnikov, Yuri A.; McAteer, James A.; VonDerHaar, R. Jason; Pishchalnikova, Irina V.; Williams, James C.; Evan, Andrew P.

doi:10.1016/j.juro.2006.07.055

Cited by 20 publications

(20 citation statements)

References 12 publications

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“…For measures of rise time the optical fiber tip was oriented parallel to the SW-path so that the wave front would hit the leading face of the fiber tip and give the shortest temporal resolution, limited only by the electronics of the hydrophone. 19 An oblique angle of incidence due to even slight misalignment of the fiber tip artificially increased the rise time rendered by the FOPH. In these studies, direct visual access of the fiber tip allowed precise alignment, typically < 2-3°off axis.…”

Section: Methodsmentioning

confidence: 99%

“…Sets of 25 waveforms (8 ns sampling rate, 5000 data points per SW, shock to shock variation < -4%) were stored using a Tektronix digital oscilloscope (TDS 5034; Tektronix, Beaverton, OR) for post-processing. 19 For mapping of the acoustic field the FOPH tip was moved in steps of 1 or 2 mm over a total lateral excursion of 10-12 mm in the focal plane of the lithotripter, with collection of 25 SWs per step. Waveforms distorted by strong cavitation are easily identified and rejected by visual…”

Section: Methodsmentioning

confidence: 99%

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Effect of the Body Wall on Lithotripter Shock Waves

McAteer

Williams

et al. 2014

Journal of Endourology

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Purpose: Determine the influence of passage through the body wall on the properties of lithotripter shock waves (SWs) and the characteristics of the acoustic field of an electromagnetic lithotripter. Methods: Full-thickness ex vivo segments of pig abdominal wall were secured against the acoustic window of a test tank coupled to the lithotripter. A fiber-optic probe hydrophone was used to measure SW pressures, determine shock rise time, and map the acoustic field in the focal plane. Results: Peak positive pressure on axis was attenuated roughly proportional to tissue thickness-approximately 6% per cm. Irregularities in the tissue path affected the symmetry of SW focusing, shifting the maximum peak positive pressure laterally by as much as *2 mm. Within the time resolution of the hydrophone (7-15 ns), shock rise time was unchanged, measuring *17-21 ns with and without tissue present. Mapping of the field showed no effect of the body wall on focal width, regardless of thickness of the body wall. Conclusions: Passage through the body wall has minimal effect on the characteristics of lithotripter SWs. Other than reducing pulse amplitude and having the potential to affect the symmetry of the focused wave, the body wall has little influence on the acoustic field. These findings help to validate laboratory assessment of lithotripter acoustic field and suggest that the properties of SWs in the body are much the same as have been measured in vitro.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Effect of the Body Wall on Lithotripter Shock Waves

McAteer

Williams

et al. 2014

Journal of Endourology

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“…22 Waveforms were collected in sets of 10 to 30 shockwaves using the Fast Frame setup of a Tektronix oscilloscope (TDS 5034). 23 Waveforms that did not exhibit artifact because of cavitation interference along the fiberoptic cable were averaged after alignment to the half amplitude of the shock fronts. 24 For mapping to determine the width of the focal zone, the tip of the hydrophone was positioned in the plane of the target point of the lithotripter (140 mm distal to the spark source, 35 mm proximal to the maximum P + focal point).…”

Section: Acoustic Output Of the Lg-380 Lithotriptermentioning

confidence: 99%

Evaluation of the LithoGold LG-380 Lithotripter:In VitroAcoustic Characterization and Assessment of Renal Injury in the Pig Model

Pishchalnikov

McAteer

Williams

et al. 2013

Journal of Endourology

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Purpose: Conduct a laboratory evaluation of a novel low-pressure, broad focal zone electrohydraulic lithotripter . Methods: Mapping of the acoustic field of the LG-380, along with a Dornier HM3, a Storz Modulith SLX, and a XiXin CS2012 (XX-ES) lithotripter was performed using a fiberoptic hydrophone. A pig model was used to assess renal response to 3000 shockwaves (SW) administered by a multistep power ramping protocol at 60 SW/min, and when animals were treated at the maximum power setting at 120 SW/min. Injury to the kidney was assessed by quantitation of lesion size and routine measures of renal function. Results: SW amplitudes for the LG-380 ranged from (P + /P -) 7/-1.8 MPa at PL-1 to 21/-4 MPa at PL-11 while focal width measured *20 mm, wider than the HM3 (8 mm), SLX (2.6 mm), or XX-ES (18 mm). For the LG-380, there was gradual narrowing of the focal width to *10 mm after 5000 SWs, but this had negligible effect on breakage of model stones, because stones positioned at the periphery of the focal volume (10 mm off-axis) broke nearly as well as stones at the target point. Kidney injury measured less than 0.1% FRV (functional renal volume) for pigs treated using a gradual power ramping protocol at 60 SW/min and when SWs were delivered at maximum power at 120 SW/min. Conclusions: The LG-380 exhibits the acoustic characteristics of a low-pressure, wide focal zone lithotripter and has the broadest focal width of any lithotripter yet reported. Although there was a gradual narrowing of focal width as the electrode aged, the efficiency of stone breakage was not affected. Because injury to the kidney was minimal when treatment followed either the recommended slow SW-rate multistep ramping protocol or when all SWs were delivered at fast SW-rate using maximum power, this appears to be a relatively safe lithotripter.

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“…A shock wave is produced when the magnetic field causes repulsion of the membrane. It is focused with a parabolic reflector or acoustic lens [5,6]. Unlike electrohydraulic technology, which requires electrode replacement every several thousand shockwaves, electromagnetic generators last for millions of shock waves.…”

Section: Shock Wave Generationmentioning

confidence: 99%

Recent advances in lithotripsy technology and treatment strategies: A systematic review update

Elmansy

Lingeman

2016

International Journal of Surgery

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Introduction Shock wave lithotripsy (SWL) is a well – established treatment option for urolithiasis. The technology of SWL has undergone significant changes in an attempt to better optimize the results while reducing failure rates. There are some important limitations that restrict the use of SWL. In this review, we aim to place these advantages and limitations in perspective, assess the current role of SWL, and discuss recent advances in lithotripsy technology and treatment strategies. Methods A comprehensive review was conducted to identify studies reporting outcomes on ESWL. We searched for literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. Relevant articles in English published since 1980 were selected for inclusion. Results Efficacy has been shown to vary between lithotripters. To maximize stone fragmentation and reduce failure rates, many factors can be optimized. Factors to consider in proper patient selection include skin – to – stone distance and stone size. Careful attention to the rate of shock wave administration, proper coupling of the treatment head to the patient have important influences on the success of lithotripsy. Conclusion Proper selection of patients who are expected to respond well to SWL, as well as attention to the technical aspects of the procedure are the keys to SWL success. Studies aiming to determine the mechanisms of shock wave action in stone breakage have begun to suggest new treatment strategies to improve success rates and safety.

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Detection of Significant Variation in Acoustic Output of an Electromagnetic Lithotriptor

Cited by 20 publications

References 12 publications

Effect of the Body Wall on Lithotripter Shock Waves

Effect of the Body Wall on Lithotripter Shock Waves

Evaluation of the LithoGold LG-380 Lithotripter:In VitroAcoustic Characterization and Assessment of Renal Injury in the Pig Model

Recent advances in lithotripsy technology and treatment strategies: A systematic review update

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